The present invention pertains to technique for controlling a headway vehicle spacing (or vehicle-to-vehicle distance) to a preceding vehicle to a desired vehicle spacing.
A Japanese Patent Kokai Publication H11(1999)-42957 published on Feb. 16, 1999, discloses a system for sensing a vehicle spacing to a preceding vehicle with a laser radar, and controlling the engine output and transmission ratio so as to reduce a deviation of a vehicle-to-vehicle time gap calculated from the sensed vehicle spacing and vehicle speed, from a desired time gap preset with a selector switch.
In this system, the desired time gap is changed with the selector switch, and a step change in the desired time gap can cause unwanted and uncomfortable acceleration or deceleration of the vehicle.
It is an object of the present invention to provide apparatus and/or method capable of changing vehicle-to-vehicle time gap or spacing smoothly.
According to the prevent invention, a vehicle spacing control apparatus comprises:
a vehicle spacing sensor sensing an actual vehicle spacing;
a vehicle speed sensor sensing an actual vehicle speed;
a selector changing a selected vehicle-to-vehicle time gap among a plurality of discrete values; and
a controller
determining a desired vehicle-to-vehicle time gap so that the selected time gap varies at a predetermined rate in response to a change in the selected time gap,
determining a desired vehicle spacing in accordance with the desired time gap and the actual vehicle speed, and
controlling at least one of a driving force and a braking force of a controlled vehicle so as to bring the actual vehicle spacing closer to the desired vehicle spacing.
According to another aspect of the present invention, a vehicle spacing control apparatus comprises: a vehicle interval sensor, such as a vehicle spacing sensor, for measuring a spatial or temporal interval from a controlled vehicle to a preceding vehicle ahead; a selector, such as a selector switch, changing a selected vehicle-to-vehicle interval among a plurality of discrete values; and a controller determining a desired vehicle-to-vehicle interval so that the desired vehicle-to-vehicle interval varies at a predetermined rate when the selected interval is changed, and controlling a longitudinal force of a controlled vehicle so as to bring the actual vehicle-to-vehicle interval closer to the desired vehicle-to-vehicle interval.
According to still another aspect of the present invention, a vehicle spacing control process comprises: ascertaining a sensed actual vehicle-to-vehicle interval from a controlled vehicle to a preceding vehicle; ascertaining a selected vehicle-to-vehicle interval selected among a plurality of discrete values; determining a desired vehicle-to-vehicle interval so that the desired vehicle-to-vehicle interval varies at a predetermined rate when the selected interval is changed; and controlling a longitudinal force of a controlled vehicle so as to bring the actual vehicle-to-vehicle interval closer to the desired vehicle-to-vehicle interval.
According to still another aspect of the present invention, a vehicle spacing control apparatus comprises: first means for ascertaining a sensed actual vehicle-to-vehicle interval from a controlled vehicle to a preceding vehicle; second means for ascertaining a change from a first select position to a second select position in a selector for determining a selected vehicle-to-vehicle interval ; third means for responding to the change from the first select position to the second select position in the selector by varying a desired vehicle-to-vehicle interval at a predetermined rate from a first select value corresponding to the first select position to a second select value corresponding to the second select position; and fourth means for controlling a longitudinal force of a controlled vehicle so as to bring the actual vehicle-to-vehicle interval closer to the desired vehicle-to-vehicle interval.